title: Transitions in frailty status in older adults in relation to mobility: a multistate modeling approach employing a deficit count.
abstract: OBJECTIVE
  To investigate how changes in frailty status and mortality risk relate to baseline frailty state, mobility performance, age, and sex.
  
  
  METHODS
  Cohort study.
  
  
  METHODS
  The Yale Precipitating Events Project, New Haven, Connecticut.
  
  
  METHODS
  Seven hundred fifty-four community-dwelling people aged 70 and older at baseline followed up at 18, 36, and 54 months.
  
  
  METHODS
  Frailty status, assessed at 18-month intervals, was defined using a frailty index (FI) as the number of deficits in 36 health variables. Mobility was defined as time in seconds on the rapid gait test, in which participants walked back and forth over a 20-foot course as quickly as possible. Multistate transition probabilities were calculated with baseline frailty, mobility, age, and sex estimated using Poisson and logistic regressions in survivors and those who died, respectively.
  
  
  RESULTS
  In multivariable analyses, baseline frailty status and age were significantly associated with changes in frailty status and risk of death, whereas mobility was significantly associated with the frailty but not with mortality. At all values of the FI, participants with better mobility were more likely than those with poor mobility to remain stable or to improve. For example, at 54 months, 20.6% (95% confidence interval (CI)=16-25.2) of participants with poor mobility had the same or fewer deficits, compared with 32.4% (95% CI=27.9-36.9) of those with better mobility.
  
  
  CONCLUSIONS
  A multistate transition model effectively measured the probability of change in frailty status and risk of death. Mobility, age, and baseline frailty were significant factors in frailty state transitions.
authors.affiliation: Division of Geriatric Medicine Department of Mathematics and Statistics, Dalhousie University, Halifax, Nova Scotia, Canada.
authors.forename: Nader
authors.initials: N
authors.lastname: Fallah
authors.forename: Arnold
authors.initials: A
authors.lastname: Mitnitski
authors.forename: Samuel D
authors.initials: SD
authors.lastname: Searle
authors.forename: Evelyne A
authors.initials: EA
authors.lastname: Gahbauer
authors.forename: Thomas M
authors.initials: TM
authors.lastname: Gill
authors.forename: Kenneth
authors.initials: K
authors.lastname: Rockwood
mesh_terms: D000368:Aged; D005260:Female; D016330:Frail Elderly; D005684:Gait / Q000502:physiology*; D015577:Geriatric Assessment; D006801:Humans; D016015:Logistic Models; D008297:Male; D016012:Poisson Distribution; D012307:Risk Factors; D012737:Sex Factors